COMMON GUILLEMOT 487 
in winter in the North Pacific Ocean, where a form with 
a stronger beak is to be found. It also frequents the seas 
of Kurope in winter, and small numbers occasionally occur 
in the Mediterranean. 
DESCRIPTIVE CHARACTERS. 
PLUMAGE. Adult male nuptial. — Top of head, hind- 
neck, back, scapulars, and wings, shading from greyish to 
brownish-black ; cheeks, chin, ‘throat, and fore- neck, dark 
sooty-brown ; secondaries, brown, tipped with white, form- 
ing a short, narrow wing- bar ; primaries, greyish- black with 
paler inner webs; tail (of 12 feathers), brownish-black ; 
lower fore-neck, breast, abdomen, under tail- and wing- 
coverts, white; flanks, white streaked with grey. 
Adult female nuptial.—Similar in plumage to the male. 
Adult winter, male and female. — Chin, throat, fore- 
neck, and cheeks, white; sides of head behind the eye also 
white, bounded below by a narrow post-ocular dark greyish- 
black band. 
Immature, male and female.—Resembles the adult winter- 
plumage, except that the white on the sides of the head and 
fore-neck is mottled with dusky-brown. 
Beak. Blackish, lighter at the base of the lower segment. 
Feet. Dark brownish-black behind and on both sides of 
the webs; front of the tarso-metatarsus and toes, brownish- 
white. 
Tr1DES. Brownish-black. 
AVERAGE MEASUREMENTS. 
TOTAL LENGTH ... .. 18 in. Female smaller. 
WING Opes 
BEAK icc. eee 
T'ARSO-METATARSUS cae Aig 
i Dreres 3°25 x 2 in 
Allied Species and Representative Forms.—The Ringed 
or Bridled Guillemot is not a distinct species, and inter- 
mixes with thousands of the Common form. It is so named 
because its eyelids are margined with white, and there is a 
white stripe in the furrow behind them. 
